The present invention relates to hydrocyclones for separating solid from liquids and particularly to cyclones for degritting water used in applications such as laboratories, air conditioning systems, household use and the like.
Cyclones are widely used for separating solids from liquids. A cyclone separator comprises a generally cylindrical/conical shell having a tangentially positioned inlet for fluid infeed and outlets for underflow and overflow. In the cyclone the fluid stream is forced to spiral inward and upwardly through a centrally located overflow outlet in the form of a purified liquid stream. The grit or heavy particles carried by the liquid are flung outward against the wall of the cone by reason of the vortex action and centrifugal force. The solids exit the cyclone through the apex of the cone as underflow. Ordinarily, a small perentage of the grit remains in the liquid spiraling inward and is carried with the overflow.
Underflow solids collectors called grit pots are used in applications where the feed solid fraction expected to be classified to the underflow is relatively small and the continuous loss of liquid to the underflow is undesirable. Once the solid concentration in the grit pot reaches a level at which the overflow quality of the cyclone can be affected, the pot is purged.
It is known that grit pots change the separation performance of cyclone separators due to the dilutriating effect on the enclosed underflow. That is, liquid which would normally discharge through the apex of the cyclone is reversed so that the liquid entering the overflow contains an increased grit content.
The performance of cyclones depends on a number of variables including cyclone diameter, liquid feed inlet diameter, vortex finder diameter,the pressure differential between inflow and overflow liquid streams, as well as characteristics of the liquid and particles to be separated. Generally speaking, small diameter cyclone separators require pressure drops between feed inlet and overflow of 20 psig or greater for their effectiveness. Hydrocyclones presently in use are not fully adequate in performance especially where low pressure small diameter cyclones are used in household applications for degritting water for household use including drinking water and for household applicances such as washing machines and so forth.
The present invention is directed to a cyclone separator for removal of grit from household water supply utilizing small diameter cyclones operating at low pressure differentials as between feed inlet and overflow. The invention also provides for improved separation performance of hydrocyclones fitted with grit pots.